Your children need one sane parent. It is not going to be your w any time soon so it has to be you. Stop the texting. Stop engaging her. She will not be reasonable or sane for a long time. If this is mlc then it has to run its course. You cannot shorten it but you can prolong it. The more you antagonize the deeper into the crises she will go. You are giving her ammunition to keep behaving the way she is.
Do as others have suggested. Set up a schedule for the children. When it is your days then you take them no matter what.
If you do not stop now you will drive yourself crazy and your children are caught in the middle.
Please Phil you need to get a grip here. You need to be the adult.